Increasing evidence from animal models to clinical studies have demonstrated the neurotoxicity of all inhalation anesthetic agents, which can produce apoptosis, prevent synaptogenesis, enhance neuro-inflammatory process and disturb Tau and aB1 production that link to Alzheimer's disease. The detrimental effect is especially troublesome in brain tissue of the young and elderly, which may further magnify and complicate their clinical primary pathology and jeopardize their long-term mental and physical wellbeing. Unfortunately, there is no known inhalation agent that is neuro-safe, and there are no known methods that can prevent detrimental effects from occurring if general anesthesia is indicated for a diagnostic or surgical procedure. Furthermore, the neurotoxity of inhalation agents are dose dependent, which depend on the concentration as well as the duration of the exposure.
In light of the above new knowledge and the well-known safety and effectiveness profile of all regional anesthesia procedures, regional anesthesia is becoming more common alone or in combination with general anesthesia because it can effectively avoid or reduce the exposure of inhalation agents. The traditional dogma that general anesthesia is indicated for all who want it for their procedure is now under question, and more and more surgeons and using physicians have started to recommend their patients to consider regional anesthesia as part of their surgical care.
Regional anesthesia includes a wide variety of techniques that can be classified into two broad categories: central neuraxial nerve block and peripheral nerve bock. Spinal and epidural anesthesia are the two most common forms of central neuraxial nerve block. Peripheral nerve block includes a wide variety of procedures that target sensory or motor nerves peripheral to the spine canal. Nerve block is a fast growing area of anesthesia due to the improvement and quick adoption of ultrasound technology. However, inadvertent vascular puncture and unrecognized intravascular catheter migration are not uncommon, which may lead to local anesthetic toxicity and cause generalized seizure and cardiac arrest as well as failed nerve block.
The recent improvements in ultrasound guided nerve block, both central and peripheral, have popularized the procedure, but have failed to change the traditional clinical practice. Clinicians are still facing the same dilemma: The choice of single shot versus continuous nerve block, and receiving the same outcome: either too short or too long of duration of nerve block. A single shot nerve block can last as short as 4 hours or as long as 24 hours depending on the location of nerve block, medication used, and patient characteristics. Continuous nerve block is inherently difficult to perform, expensive, and outcomes are unpredictable due to catheter migration. As a result, nerve block is used purely as a pain management procedure during surgery or recovery, which is often at odds with functional recovery of a surgical patient. For example, prolonged femoral nerve block in total knee replacement (TKR) surgery can increase the risk of fall, delay rehabilitation, and prolong the length of hospital stay (LHS). On the other hand, ineffective femoral nerve block in TKR can also delay the rehabilitation, prolong the LHS, decrease patient satisfaction, and increase hospital cost.
Relevant art: US 20110218529; US 20070270928; and US 20010025169.